Hydrocyanation of olefins

ABSTRACT

Process of isomerizing 3-pentenenitriles to 4-pentenenitrile using compounds of iron, or ruthenium having a valence of +2 or less as a catalyst and of adding hydrogen cyanide to carboncarbon double bonds such as in 4-pentenenitrile at from -25* to 200*C using as catalysts ruthenium or iron compounds having a valence of +2 or less.

Unite States Patent Drinkard, Jr. et al. [4 1 Sept. 26, 1972 HYDROCYANATION OF OLEF INS 721 inventors: William c. Drinkard, Jr., Wilming- [561 References cied Verona, Pa. [73] Assignee: E. l. du Pont de Nemours and Company, Wilmington, Del. r '[221 File April 2 1 10 Primary ExaminerJoseph P. Brust 211 pp N 43 2 4 Att0rney-William A. Hoffman Related US. Application Data [57] ABSTRACT Division Of b 1969, Process of isomerizing 3-pentenenitriles to 4-pen- Pal which is a continuation-intenenitrile using compounds of iron, or ruthenium P of No. 630,947, 1967, abanhaving a valence of +2'or less as a catalyst and of addonedding hydrogen cyanide to carbon-carbon double bonds such as in 4-pentenenitrile at from 25 to 200C [52] CL R, 260/465 260/465 H, using as catalysts ruthenium or iron compounds hav- 260/4653 ing a valence of +2 or less. [51] Int. Cl. ..C07c 121/04, C07c 121/26 [58] Field of Search...260/465.3, 465.6, 465.9, 465.8 3 Claims, No Drawings HYDROCYANATION F OLEFINS This application is a division of application Ser. No. 857,535, filed on Sept. 12, 1969, by William C. Drinkard, Jr. and Brian W. Taylor, now US. Pat. No. 3,551,474, which in turn is a continuation-in-part of application Ser. No. 680,947 filed on Nov. 6, 1967, by the same inventors, now-abandoned.

DESCRIPTION OF THE PRIOR ART It is known that the addition of hydrogen cyanide to double bonds adjacent an activating group such as a nitrile or acyloxy group, proceeds with relative ease. However, the addition of hydrogen cyanide to nonactivated double bonds proceeds only with difficulty, if at all, and normally requires the use of high pressures of about 1,000 psi or more and high temperatures in the range of 200 to 400 C. US. Pat. No. 2,583,984, issued Jan. 29, 1952 to Paul Arthur, Jr., discloses a technique which involves the use of cuprous cyanide and either ferric chloride or ferric bromide for the hydrocyanation of butadiene. This process is not satisfactory for the production of adiponitrile from 3- or 4-pentenenitrile. The-selective formation of 4-pentenenitrile from 3-pentenenitriles without formation of the thermodynamically more stable Z-pentenenitrile is believed to be unknown in the art.

SUMMARY OF THE INVENTION The present invention provides a process or a step in i a process which produces nitriles or dinitriles from as butadiene or allene, monoolefins and monoolefins substituted with groups which do not attack the catalyst such as cyano. These unsaturated compounds include monoolefins containing from two to 20 carbon atoms such as ethylene, propylene, butene-l, pentene-2, hexene-2, etc., and substituted compounds such as styrene, a-methyl styrene, 3-pentenenitrile, and 4-pentenenitrile. The process also finds special advantage in the production of 2-methyl-glutaronitrile from 2- methyl-3-butenenitrile.

In the preferred process of the present invention wherein adiponitrile is formed from 3-pentenenitrile, the reaction proceeds in two steps. The first step involves the isomerization of 3-pentenenitrile to 4-pentenenitrile. It is followed by the addition of hydrogen cyanide to 4-pentenenitrile to form adiponitrile.

The first step is catalyzed by iron or ruthenium compounds having a valence of +2 or less such as ruthenium pentacarbonyl, iron pentacarbonyl, Fe (CO) Fe (CO), Fe(CO) l and the hereinbelow defined compounds for the second step.

A preferred class of catalysts have the structure [LmMXmh er in M is te mmhq la s an-.- sisting of Fe and Ru, X is an anion, preferably a chloride, iodide, or cyanide, L is a neutral pi bonding ligand,

n sa nu edcalv lu o ro 2 t tth m of n and m is from 4 to 5 and b has a numerical value of from 1 to 3. The ligands useful as L may be defined as any atoms or molecule capable of functioning as a sigma/pi bonded partner in one or more coordinate bonds. A description of such ligands may be found in Advanced inorganic Chemistry" by F. Albert Cotton and G. Wilkinson, published by Interscience Publishers, a division of John Wiley & Sons, 1962, Library of Congress Catalog Card No. 62-14818; particularly on pages 602-606. A preferred class of such ligands includes CO and compounds having the formula PZ, wherein Z is selected from the class consisting of R and OR wherein R is selected from the class consisting of alkyl andaryl radicals having up to 18 carbon atoms. These same catalysts, particularly in the case where M is Ru, are suitable for use in the hydrocyanation reaction. Preparations of these catalysts may be found in Advances in Inorganic Chemistry and Radiochemistry, by G. Booth, published by Academic Press, Vol. 6, 1964, Library of Congress Catalog Card No. 59- 7692, particularly on pages 13-20.

Both the hydrocyanation reaction or the isomerization of 3-pentenenitrile can be carried out with or without a solvent. The solvent should be a liquid at the reaction temperature and inert towards the unsaturated compound and the catalyst. Generally, such solvents are hydrocarbons such as benzene, xylene, or nitriles such as acetonitrile, benzonitrile, .or adiponitrile.

The exact temperature used is dependent, to a certain extent, on the particular catalyst being used, the particular unsaturated compound being used and the desired rate. Generally, temperatures of from 25C. to 200C. can be used with from 0C. to C. being the preferred range for both the isomerization of 3-pentenenitrile and the hydrocyanation of unsaturated compounds.

Either reaction may be carried out by charging a reactor with all of the reactants. In case of hydrocyanation, preferably the reactor is charged with the catalyst or catalyst components, the unsaturated compound and whatever solvent is to be used and the hydrogen cyanide gas is swept over the surface of the reaction mixture or bubbled into the reaction mixture or it may be introduced in liquid form. If desired, when hydrocyanating a gaseous unsaturated organic compound, the hydrogen cyanide and the unsaturated organic compound may be fed together into the reaction medium. The molar ratio of unsaturated compound to catalyst generally is varied from about 10:1 to 2000:1 unsaturated compound to catalyst for a batch operation. In a continuous operation such as when using a fixed bed catalyst type of operation, a much higher proportion of catalyst may be used such as 1:2 unsaturated compound to catalyst.

Optionally, a promoter may be used to activate the catalyst for the hydrocyanation reaction. The promoter generally is a boron compound or a cationic form of a metal selected from the class consisting of zinc, cadmium, beryllium, aluminum, gallium, indium, thallium, titanium, zirconium, hafnium, orbium, germanium, tin, vanadium, niobium, scandium, chromium, molybdenum, tungsten, manganese, rhenium, palladium, thorium, and cobalt. The preferred boron compounds are borohydrides and organoboron compounds of which the preferred borohydrides are the alkali metal borohydrides and the quaternary ammonium borohydrides particularly the tetra (lower alkyl) ammonium borohydrides. Other suitable promoters are salts of the metals listed above and include aluminum chloride, zinc chloride, cadmium iodide, titanium trichloride, titanium tetrachloride, zinc acetate, ethyl aluminum dichloride, chromic chloride, stannous chloride and zinc iodide. The promoter acts to improve catalyst efficiency and, in certain cases, such as the hydrocyanation of 3- or 4-pentenenitrile to adiponitrile, can result in an improved yield.

If desired, an excess of a ligand such as an aryl phosphite or phosphine may also be added to the reaction mixture.

Preferably, the reaction mixture is agitated, such as by stirring or shaking.

The hydrocyanated product can be recovered by conventional techniques such as crystallization of the product from solution or by distillation.

The nitriles formed by the present invention are useful as chemical intermediates. For instance, adiponitrile is an intermediate used in the production of hexamethylene diamine which is used in the production of polyhexamethylene adipamide, a commercial polyamide, useful in forming fibers, films and molded articles. Other nitriles can be converted to the corresponding acids and amines which are conventional commercial products.

DESCRIPTION OF THE PREFERRED EMBODIMENTS EXAMPLE I A 50 ml, three-necked round bottom glass flask, fitted with a water cooled reflux condenser connected to a dry ice trap, a gas inlet above the liquid level, and a magnetic stirrer is set up in an oil bath maintained at 100C. The flask is purged with nitrogen gas and charged with 1.0 mmole [(C H P] RuCl 2.0 mmole of SnCl and 20 g of 3-pentenenitrile. A stream of nitrogen gas is bubbled through liquid hydrogen cyanide contained in a 20 ml flask cooled in an ice bath. The resulting gas mixture is swept across the surface of the reaction mixture in the flask. The nitrogen gas flow is adjusted so that 0.2 ml per hour of hydrogen cyanide (measured as a liquid at C.) is fed to the reaction flask. After 16.5 hours the reaction is shut down.

Gas chromatographic analysis indicates that the crude reaction mixture contains adiponitrile and 2- methylglutaronitrile.

EXAMPLE ll A 50 ml, three-necked round bottom glass flask, fitted with a water cooled reflux condenser connected to a dry ice trap, a gas inlet above the liquid level, and a magnetic stirrer is set up in an oil bath maintained at 100C. The flask is purged with nitrogen gas and charged with 1.0 mmole of [(C H P] RuCl 2.0 mmoles of ZnCl and g. of 3-pentenenitrile. A stream of nitrogen gas is bubbled through liquid hydrogen cyanide contained in a 20 ml flask cooled in an ice bath. The resulting gas mixture is swept across the surface of the reaction mixture in the flask. The nitrogen gas flow is adjusted so that 0.1 ml per hour of 4 hydrogen cyanide (measured as a liquid at 0C..) is fed to the reaction flask. After 16.5 hours the reaction is shut down.

Gas chromatographic analysis indicates that the crude reaction mixture contains adiponitrile. and 2- methylglutaronitrile.

EXAMPLE [[1 A 50 ml, three-necked round bottom glass flask, fitted with a water cooled reflux condenser connected to a dry ice trap, a gas inlet above the liquid level, and a magnetic stirrer is set up in an oil bath maintained at C. The flask is purged with nitrogen gas an charged with 2.0 mmoles of [(C l-l P] RuCl 2.0 mmoles of ZnCI l0 mmoles of EXAMPLE IV A 50 ml, three-necked round bottom glass flask, fitted with a water cooled reflux condenser connected to a dry ice trap, a gas inlet tube above the liquid level, and a magnetic stirrer is set up in an oil bath. The flask is purged with nitrogen gas and charged with 0.39 g. of Fe(CO) 1.0 ml. of glyme, and 20 g. of 3-pentenenitrile, and further purged with nitrogen gas after which the oil bath is heated to 100C. for 2 hours at which time the reaction is shut down.

Gas chromatographic analysis indicates that the crude reaction mixture contains 10 per cent 4-pentenenitrile.

EXAMPLE V A 50 ml, three-necked round bottom glass flask, fitted with a water cooled reflux condenser connected to a dry ice trap, a gas inlet tube above the liquid level, and a magnetic stirrer is set up in an oil bath. The flask is purged with nitrogen gas and charged with 0.39 g. of Fe(CO) and 20 g. of 3-pentenenitrile and further purged with nitrogen gas, after which the oil bath is heated to 100C. for 2 hours at which time the reaction is shut down.

Gas chromatographic analysis indicates that the crude reaction mixture contains 10 per cent 4-pentenenitrile.

EXAMPLE VI A 50 ml, three-necked round bottom glass flask, fitted with a water cooled reflux condenser connected to a dry ice trap, a gas inlet tube above the liquid level, and a magnetic stirrer is set up in an oil bath. The flask is purged with nitrogen gas and charged with 0.96 g. of

tenenitrile, and further purged with nitrogen gas after which the oil bath is heated to 100C. for 72 hours at which time the reaction is shut down.

Gas chromatographic analysis indicates that the crude reaction mixture contains per cent 4-pentenenitrile.

For Examples VII, VIII and IX, the apparatus and procedure are as described for Example I.

EXAMPLE VII The reaction flask is charged with 1.0 g. of RuCl 0.33 g. of Zn dust, 6.2 g. of P(OC I-I and g. of 3- pentenenitrile. The mixture is maintained at 100C. for 22 hours while HCN sweeps across the reaction at a rate of 0.4 ml/hour (measured as liquid at 0C.

Gas chromatographic analysis shows that the crude product contains 0.279 percent Z-methylglutaronitrilc.

EXAMPLE VIII The reaction flask is charged with.2.5 g. of Fe (CO) and 20 g. of 3-pentenenitrile. The mixture is maintained at 120C. for 20.5 hours while HCN sweeps across the reaction at a rate of 1.0 ml/hour (measured as liquid at 0C.).

Gas chromatographic analysis shows that the crude product contains 1.38 percent ethylsuccinonitrile.

EXAMPLE IX EXAMPLE X The reaction flask is charged with 2.0 g. of Fe (CO) and 20 g. of 3-pentenenitrile. The mixture is maintained at 80C. for 16 hours.

Gas chromatographic analysis shows that the crude product contains 3.85 percent 4-pentenenitrile.

EXAMPLE XI The reaction flask is charged with 2.0 g. of [(CH CH -,NH] [Fe l-I(CO) and 20 g. of 3-pentenenitrile. The mixture is maintained at 80C. for 16 hours.

Gas chromatographic analysis shows that the crude product contains 5.3 percent 4-pentenenit-rile.

EXAMPLE XII The reaction flask is charged with 2.5 g. Fe (CO) and 10 g. of 3-pentenenitrile. The mixture is maintained at 100C. for 2 hours.

Gas chromatographic analysis shows that the crude product contains 6.17 percent 4-pentenenitrile.

6 EXAMPLE XIII The reaction flask is charged with 3.0 g. of Fe(CO) I and 20 g. of S-pentenenitrile. The mixture is maintained at 100C. for 16 hours.

Gas chromatographic analysis shows that the crude product contains 0.22 percent 4-pentenenitrile.

EXAMPLE XIV The reaction flask is charged with 1.0 g. of

and 20 g. of B-pentenenitrile. The mixture is maintained at C. for 23 hours.

Gas chromatographic analysis shows that the crude product contains 0.99 percent 4-penetenenitri1e.

EXAMPLE XV The reaction flask is charged with 0.7 g. of I-IFe[P(O Qg H Eh Q-Z g. of I; and 10 ml. of 3- pentenenitrile. The mixture is maintained at 80C. for l 7.5 hours.

Gas chromatographic analysis shows that the crude product contains 4.4 percent 4-pentenenitrile.

EXAMPLE XVI The reaction flask is charged with -I .0 g. of Fe (CO) and 10 ml. of 3-pentenenitrile. The mixture is maintained at C. for 22 hours.

Gas chromatographic analysis shows that the crude product contains 1 l .0 percent 4-pentenenitrile.

EXAMPLE XVII The reaction flask is charged with 1.0 g. of F e (CO) and 10 ml. of 3-pentenenitrile. The mixture is maintained at 100C. for 22 hours.

Gas chromatographic analysis shows that the crude product contains 7.5 percent 4-pentenenitrile.

We claim:

1. A process of hydrocyanating an unsaturated organic compound of the group consisting of 3-pentenenitrile, 4-pentenenitrile and 2-methyl-3-butenenitrile which comprises contacting the organic compound with hydrogen cyanide and a catalyst consisting essentially of a compound having the structure lliMXmlm q M is a talglqsfiqfrqmt ass consisting of iron and ruthenium, n has a numerical value offrom 2 to 5, the sum ofn and m is from 4 to 5, b has a numerical value from I to 3, X is selected from the class consisting of chloride, iodide and cyanide, L is a sigma/pi bonding neutral ligand of the class consisting of CO and PZ wherein Z is selected from the class consisting of OR and R wherein R is an aryl group having up to 18 carbon atoms, the molar ratio of unsaturated organic compound to catalytic compound being from 1:2 to 2000:l, at a temperature of from 25C. to 200C. and forming at least one organic cyano compound by addition of hydrogen cyanide to the carboncarbon double bond of the organic compound.

2. The process of claim 1 wherein [L,,MX,,,] is ll fi laPl 3. The process of claim 1 wherein [L,,MX,,,],, is FC3(CO)12. 

2. The process of claim 1 wherein (LnMXm)b is ((C6H5)3P)3-RuCl2.
 3. The process of claim 1 wherein (LnMXm)b is Fe3(CO)12. 